This invention relates to an apparatus for handling conveyed paper sheets inclusive of bank notes. Examples of the paper sheet handling apparatus include an apparatus for sensing the parameters of paper sheets (parameters such as thickness, length, the existence of skew and, if skew exists, the angle of skew), and an apparatus which uses sensed parameters to count the number of paper sheets and release the number of paper sheets counted. The paper sheet handling apparatus is provided, for example, in a transaction processing unit such as an automated teller's machine (ATM) or automatic cash dispenser (CD). A specific example of the apparatus is a machine for releasing or discharging bank notes.
A bank note releasing machine is adapted to release or discharge a given number of bank notes and is equipped with a bank note thickness detector which, in order to assure that the released bank notes are counted correctly, senses whether the bank notes are being conveyed one at a time or whether two or more bank notes are superimposed while being conveyed. Such thickness detectors are either of a mechanical type using a cam or of an optical type relying upon a photosensor.
One type of the mechanical arrangement has a freely rotatable cam arranged between opposing members leaving a gap equivalent to the thickness of a single bank note. When two or more superimposed bank notes are conveyed past the cam, the latter rotates to sense the event. Thus, this arrangement is only capable of sensing the passage of one bank note or more than one bank note. Accordingly, the conventional bank note releasing machine performs a bank note releasing operation only if passage of one bank note is determined; if two or more bank notes are superimposed, these are recovered or collected within the machine without being released. The mechanical arrangement using the cam also has a number of other drawbacks. For example, in order for it to be applied to a wide variety of bank notes of different thicknesses, one arrangement must be provided for each type of bank note. Reliability is low with regard to bank notes having a large variation in thickness, as is the case when one and the same note has a thickness that differs depending on the location. In addition, the sensed thickness varies depending upon the frictional coefficient of the bank notes, and sensing errors occur due to bank notes whose edges are folded or which are wrinkled. Moreover, length in the direction of note conveyance cannot be measured.
The optical arrangement is adapted to sense two superimposed bank notes by measuring the amount of transmitted light in the thickness direction of the bank notes. The problem with this expedient is poor reliability caused by bank notes which are soiled.